Visualization apparatuses are a necessary prerequisite for surgical procedures on very small and fine body structures. Such operations may even involve the participation of two observers or surgeons who, for example in spinal operations, are situated opposite one another in a 180° arrangement.
Traditional visualization apparatuses form surgical microscopes that are typically arranged directly between observer and an operation site. With the use of digital visualization apparatuses, by contrast, the operation site is recorded by an image recording unit and represented in a magnified fashion for each observer on an image representation unit.
U.S. Pat. No. 5,867,210 describes a method for representing images of a stereoscopic surgical microscope with a video camera. The image of the video camera is displayed on a first image representation unit for a first observer and a second image representation unit for a second observer. Both observers have to wear special spectacles in order to be able to view a stereoscopic image.
What is disadvantageous about this method is that a dedicated image representation unit has to be present for each observer. The image representation units occupy a relatively large amount of space and can lead to a restriction of the working space and the freedom of movement of the observer or of the respective other observer. Each change of view between operation site and image representation unit involves a head movement and an accommodation of the eyes of the observer. For observers aged 40 or more, there is an increasing reduction in the elasticity of the eye lens, and the accommodation times increase as a result. A head movement governed by the arrangement of the image representation unit, and the changing accommodation of the eyes that is associated therewith can lead to unergonomic work. The consequence is more rapid fatigue of the observer.
For observers with presbyopia, it is possible that either the operation site or the image representation unit no longer lies in the accommodation range of the observer, such that the observer requires further aids such as varifocal spectacles, for example, in order to be able to accommodate to the operation site and the image representation unit. However, the use of varifocal spectacles is disadvantageous because objects at a specific distance can be observed well thereby only at a specific viewing angle.